I'm up to episode 7. Episodes 5-7 were a noticeable improvement over the first four. I think the show will likely suffer from its 13 episode length though, as I don't think they'll have the time to develop the whole cast, do the story justice, and feel like a real globe-trotting adventure. In terms of the last part, having double the amount of episodes would help because I think some of these episodes' plots would benefit from being expanded into two-parters. Instead, pretty much every episode starts with them comfortably back at their HQ, which I feel hurts the feel of the global scale of the search.
Like, the cult episode was good and I feel the hacker girl is the one main character to actually get a bit fleshed out so far, but they could have made it a two-parter, actually give hacker girl some flashbacks of her past life at the commune so we can connect more to her, made it more of a mystery (like the outside world's theory is that their "god" is an AI but it's not confirmed, and as the two heroes spend time in the commune they see the higher priest do a few things that seem like unexplainable miracles, but in the end the two heroes discover the AI and it's revealed how the priest pulled off the "miracles"), give her more time to bond with the one girl in the cult who ends up helping them so that moment of her turning away from the cult feels more impactful, etc.
Too much of the show feels rushed and things that should be visually displayed through flashbacks and such are just told instead through quick exposition which is generally less effective in making me care about the characters. I will say I really did like them each at different points in the ocean in episode 7, appreciating the beauty of the natural world and wondering if Skinner is deliberately showing them the journey that he took that shaped his mindset. That's good stuff, but again the show doesn't feel like it has enough time to really explore this fully.
So yeah, in terms of the Watanabe shows I've seen, this is the weakest from what I've seen so far. Cowboy Bebop is a 10, Samurai Champloo and Space Dandy are both a 9, Carole and Tuesday is a 8, but I can only give this a 7 at most so far. The animation is mostly great and the music is pretty good, and I am liking the show a bit more as it goes on, but those first few episodes particularly needed restructuring and such, and ultimately I think this show's 13 episode length will hurt it.